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Assertion : D-glucose is dextrorotatory ...

Assertion : D-glucose is dextrorotatory whereas L-glucose is laevorotatory.
Reason : D-compounds are always dextro and L-compounds are always laevorotatory

A

If both assertion and reason are true and reason is the correct explanation of assertion.

B

If both assertion and reason are true but reason is not the correct explanation of assertion.

C

If assertion is true but reason is false.

D

If both assertion and reason are false.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question, we need to analyze both the assertion and the reason provided. ### Step 1: Analyze the Assertion The assertion states that "D-glucose is dextrorotatory whereas L-glucose is laevorotatory." - D-glucose is indeed dextrorotatory, meaning it rotates plane-polarized light to the right (clockwise). - L-glucose is levorotatory, meaning it rotates plane-polarized light to the left (counterclockwise). - Therefore, the assertion is **true**. ### Step 2: Analyze the Reason The reason states that "D-compounds are always dextro and L-compounds are always laevorotatory." - This statement is **not true**. While D-glucose is dextrorotatory, not all D-compounds are necessarily dextrorotatory. For example, D-fructose is levorotatory. - Similarly, not all L-compounds are levorotatory. The rotation depends on the specific structure and configuration of the molecule, not solely on the D or L designation. - Therefore, the reason is **false**. ### Step 3: Conclusion Since the assertion is true and the reason is false, we conclude that the correct answer is that the assertion is correct, but the reason is incorrect. ### Final Answer: Assertion is true; Reason is false.
To solve the question, we need to analyze both the assertion and the reason provided. ### Step 1: Analyze the Assertion The assertion states that "D-glucose is dextrorotatory whereas L-glucose is laevorotatory." - D-glucose is indeed dextrorotatory, meaning it rotates plane-polarized light to the right (clockwise). - L-glucose is levorotatory, meaning it rotates plane-polarized light to the left (counterclockwise). - Therefore, the assertion is **true**. ...
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Assertion (A) D(+)- Glucose is dextrorotatory in nature. Reason (R) 'D' represents its dextrorotatory nature. (a)Assertion and reason both are correct statements and reason explains the assertion. (b)Both assertion and reason are wrong statements (c)Assertion is correct statement and reason is wrong statement (d)Assertion is wrong statement and reason is correct statement.

The structure of D-(+)- glucose is The structure of L-(-)- glucose is

Knowledge Check

  • Assertion : Glucose is correctly named as D-(+)-glucose. ' 3 Reason : ‘D’ before the name of glucose represents its dextrorotatory nature.

    A
    If both assertion and reason are true and reason is the correct explanation of assertion.
    B
    If both assertion and reason are true but reason is not the correct explanation of assertion.
    C
    If assertion is true but reason is false.
    D
    If both assertion and reason are false.

  • The d- and l- forms of an optically active compound are called

    A
    enantiomers
    B
    diastereoisomers
    C
    anomers
    D
    epimers

  • Assertion: Hydrolysis of sucrose brings about a change in sign of rotation from dextro to laevo. Reason: Hydrolysis always changes the optical rotation of a compound.

    A
    If both assertion and reason are true and reason is the correct explanation of assertion.
    B
    If both assertion and reason are true but reason is not the correct explanation of assertion.
    C
    If assertion is true but reason is false.
    D
    If both assertion and reason are false.

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    Assertion : A solution of sucrose in water is dextrorotatory. But on hydrolysis in the presence of a little hydrochloric acid, it becomes laevaorotatory. Reason : Sucrose on hydrolysis gives unequal amounts of glucose and fructose. As a result of this, change in sign of rotation is observed.

    Compound which rotates the plane polarised light is known as optically active compound . On the basis of direction of rotation two forms of an optically active compounds are termed as dextro and laevo rotatory . The two are termed as enantiomers . If we have a 1 : 1 mixture of d and l isomers of a given chiral compound , optical rotation of such mixture is zero Such a mixture is optically inactive and is called a recemic modification. The net specific rotation of any mixture of the d and isomers of a given chiral compound is equal to the weighted average of the rotations due to both the isomers Mathematically if can be expressed as : [alpha]_(net) =f_(d) [alpha_(d)] + f_(1) [alpha_(l)] Where f_(a) and f_(l) are fractions of d and l isomers respectively and [alpha_(d)] , [alpha_(l)] are their specific rotations The pure d isomer of certain chiral compound has [alpha]_(d)^(25) =+ 55^(@) .A non racemic mixture of this compound has a net [alpha]_(d)^(25) =- 11^(@) . What is the fractions of this isomer in mixture ?

    Assertion (A): Calmel is a chemical compound whereas brass is a mixture. Reason (R ): Calomel always contains 5.6 times as much mercury as chlorine by weight. Brass can be made with widely different ratios of copper and zine.

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